Wireless telecommunication using subframes

ABSTRACT

A network base station can select, for each of one or more attached terminals, a respective downlink transmission mode (DTM) based at least in part on respective channel condition information (CCI). The base station can determine a subframe allocation of DTMs to subframes of a radio frame, and transmit downlink data to terminals based the subframe allocation. Additionally or alternatively, the base station can receive load information from a second base station associated with a different access network and determine the subframe allocation based on the load information. The subframe allocation can associate a specific access network with each subframe. Additionally or alternatively, the base station can send the subframe allocation to the second base station. Additionally or alternatively, the base station can determine a proportion of GBR traffic of a particular DTM, determine a reference-signal transmission rate associated with that DTM, and transmit reference signals accordingly.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application which claims priority to commonlyassigned, co-pending U.S. patent application Ser. No. 16/182,100, filedNov. 6, 2018. Application Ser. No. 16/182,100 is fully incorporatedherein by reference.

BACKGROUND

In a telecommunications network, a terminal can wirelessly connect to abase station in order to engage in voice calls, video calls, datatransfers, or other types of communications. For example, a terminal canconnect to an eNodeB (eNB) of a Long Term Evolution (LTE) network.

A base station can transmit radio frames that include data for aterminal based on a selected transmission mode (abbreviated “TM”). Thebase station may select a particular transmission mode for a terminal'sdata in a radio frame based on signal quality metrics reported by theterminal, as some transmission modes can provide higher throughput tothe terminal than other transmission modes in different situations.However, the terminal may only be able to correctly interpret a receivedradio frame if it has information about which transmission mode the basestation actually selected and used for the terminal's data in that radioframe.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is set forth with reference to the accompanyingfigures. In the figures, the left-most digit(s) of a reference numberidentifies the figure in which the reference number first appears. Theuse of the same reference numbers in different figures indicates similaror identical items. The attached drawings are for purposes ofillustration and are not necessarily to scale. For brevity ofillustration, in the diagrams herein, an arrow beginning with a diamondconnects a first component or operation (at the diamond end) to at leastone second component or operation that is or can be included in thefirst component or operation.

FIG. 1 is a block diagram illustrating a system for implementing networksubframe-based communication according to some implementations.

FIG. 2 is a block diagram illustrating a system that providessubframe-based communication according to some implementations.

FIG. 3 illustrates an example process for allocating radio resources andtransmitting data according to some implementations.

FIG. 4 illustrates example processes for allocating radio resources andtransmitting data according to some implementations.

FIG. 5 illustrates example processes for allocating radio resources andtransmitting control signals according to some implementations.

FIG. 6 illustrates an example process for controlling the transmissionof reference signals according to some implementations.

FIG. 7 illustrates example processes for controlling the transmission ofreference signals according to some implementations.

FIG. 8 illustrates example processes for transmitting downlink dataaccording to some implementations.

FIG. 9 illustrates an example process for receiving data duringMultimedia Broadcast Multicast Service (MBMS) Single Frequency Network(MBSFN) subframes according to some implementations. For clarity,control flow is shown using solid lines and dataflow is shown usingdashed lines.

FIG. 10 illustrates an example process for receiving data in non-MBSFNsubframes according to some implementations. For clarity, control flowis shown using solid lines and dataflow is shown using dashed lines.

DETAILED DESCRIPTION Overview

A telecommunication network can include base stations, such as eNodeBs(eNBs) in an LTE network, that wirelessly communicate with userequipment (UE) or other terminals in cells serviced by the basestations. Some base stations can be configured to support multipletransmission modes. For example, base stations can be set up to use oneof 3GPP's Transmission Mode Four (TM4) or Transmission Mode Nine (TM9)when transmitting data for individual terminals in radio frames. In manycases, TM4 can lead to higher throughput than TM9 when a terminal iscloser to the base station, whereas TM9 can lead to higher throughputthan TM4 when the terminal is farther away from the base station.

In some examples, a base station divides subframes of a radio frameamong multiple transmission modes. For example, the MBMS specificationpermits allotting up to six of the ten subframes in an LTE radio frameas MBSFN subframes. Some prior schemes require an entire frame use asingle transmission mode. In various examples herein, the MBSFNsubframes can have a different transmission mode than the non-MBSFNsubframes, e.g., TM9 and TM4, respectively. This can provide improvedcoverage or throughput to terminals both closer to the base station andfarther from the base station. Accordingly, the term “MBSFN subframes”herein refers to subframes identified in network configurationinformation (e.g., system information block 2, SIB2) as MBSFN subframes,even if the data transmitted in those subframes does not match the MBMSformat (e.g., is not carried via the physical MBMS channel, PMCH).

However, in some prior schemes, the number of MBSFN subframes per frameis statically provisioned. In those schemes, it is not possible toadjust the number of sub frames of a service to match the number ofterminals actually using that service. This can lead to under-loaded andover-loaded subframes. Therefore, these prior schemes suffer a reductionin capacity when the services requested by the terminals do not matchthose provisioned.

In various examples herein, by contrast, the base station can change thenumber of MBSFN subframes each frame to match the spatial distributionof terminals attached to that base station. If most of the terminals arerelatively farther away from the base station, a relatively largernumber of MBSFN subframes can be used, those subframes carrying trafficusing TM9. By contrast, if most of the terminals are relatively closerto the base station, a relatively smaller number of MBSFN subframes canbe used. Therefore, the number of non-MBSFN, TM4 subframes can berelatively larger. Adjusting the number of MBSFN subframes dynamicallypermits adapting the mix of transmission modes to the spatialdistribution of terminals, which can increase the capacity of the basestation or the quality of service provided to those terminals.

During a TM9 subframe, the base station transmits reference signals,e.g., terminal-specific reference signals such as demodulation referencesignals (DMRS or DM-RS) or channel-state information reference signals(CSIRS or CSI-RS). These signals permit determining characteristics ofthe radio-frequency (RF) channel between the base station and theterminal. However, these signals also consume transmission resourcesthat are then unavailable for user data. In various examples, the basestation changes how often CSI-RS signals are sent depending on the typesof sessions active at a particular time (although the type or content ofthe CSI-RS signals does not depend on the types of sessions, in someexamples). For example, if relatively more guaranteed bit-rate (GBR)sessions are active, CSI-RS signals can be transmitted more often. Thiscan provide more accurate channel information, and so can permitadjusting transmission mode or other transmission characteristics toprovide those sessions with their guaranteed bit rates. If relativelyfewer GBR sessions are active, CSI-RS signals can be transmitted lessoften. This can provide more transmission resources (e.g., resourceelements, REs) for user data transmission. In various examples, thistype of reference-signal periodicity adjustment is used together withMBSFN subframe-count adjustment, as described above, to further increasecapacity.

Some recent LTE and New Radio (NR) (3GPP 5G) systems use full-dimensionmultiple-input/multiple-output (FD-MIMO) techniques and antennaconfigurations (e.g., single-user, SU-MIMO, or multi-user, MU-MIMO).FD-MIMO configurations permit, for example, transmitting to a particularterminal in a relatively narrower RF beam directed to that terminalrather than in a relatively wider beam or an omnidirectional radiationpattern. This can increase capacity by permitting simultaneous,overlapping transmissions to different terminals, distinguished by theirbeam directions.

In various examples, capacity is further increased by using MBSFNsubframe-count adjustment with FD-MIMO, or by using CSI-RS periodicityadjustment with FD-MIMO, or by using both MBSFN subframe-countadjustment and CSI-RS periodicity adjustment with FD-MIMO. Variousexamples herein can be used in LTE-only deployments, NR-onlydeployments, Evolved Universal Terrestrial Radio Access (E-UTRA)-NR DualConnectivity (EN-DC) deployments, or other LTE/NR overlaid deployments.In EN-DC configurations, one of the LTE and the 5G can be allocated inthe MBSFN subframes, and the other can be allocated in the non-MBSFNsubframes (e.g., LTE in the MBSFN).

As used herein, a “terminal” is a communication device, e.g., a cellulartelephone or other UE, configured to perform, or intercommunicate withsystems configured to perform, techniques described herein. Terminalscan include, e.g., wireless voice- or data-communication devices. Aterminal can include a user interface (e.g., as does a smartphone), butis not required to. For example, a streaming server configured toprovide audio or visual content on demand can be a terminal. Such aterminal may not include a user interface, and may instead respond toother terminals that form queries and send those queries to the serverin response to actions taken via interfaces at those other terminals.

The term “session” as used herein includes a communications path forbidirectional exchange of data among two or more terminals. Examplesessions include voice and video calls, e.g., by which human beingsconverse, a data communication session, e.g., between two electronicsystems or between an electronic system and a human being. Sessions canbe conduced using 3GPP, Signaling System 7 (SS7), CCS, or RichCommunication Suite (RCS, also known as JOYN) protocols.

Example networks carrying sessions include second-generation (2G)cellular networks such as the Global System for Mobile Communications(GSM) and third-generation (3G) cellular networks such as the UniversalMobile Telecommunications System (UMTS). Other example networks includefourth-generation (4G) cellular networks, such as LTE cellular networkscarrying voice over LTE (VoLTE) sessions using Session InitiationProtocol (SIP) signaling, fifth-generation (5G) cellular networks suchas 3GPP New Radio (NR) access networks, the PSTN using SS7 signaling,and data networks, such as Institute of Electrical and ElectronicsEngineers (IEEE) 802.11 (WIFI) networks carrying voice over InternetProtocol (VoIP) calls or other OTT sessions encapsulating, e.g., voiceor video data in a way transparent to an underlying packet transport.GSM and the PSTN are examples of circuit-switched (CS) networks; LTE andWIFI are examples of packet-switched (PS) networks. In some examples,OTT traffic, e.g., of CCS sessions, can be carried via 3G General PacketRadio Service (GPRS), 4G LTE, 5G, WIFI, or other packet networks.

Subsection headers in this Detailed Description are solely forconvenience in reading. Some examples include features from only onesubsection. Some examples include features from more than onesubsection.

Illustrative Configurations

FIG. 1 illustrates an example telecommunications network 100 and showsan overview of nodes and devices involved in provision oftelecommunication services to terminals. The telecommunications network100 includes terminals 102(1)-102(N) (individually or collectivelyreferred to herein with reference 102), N≥1. A terminal 102 may be orinclude a wireless phone, a tablet computer, a laptop computer, awristwatch, or another type of terminal such as those described above.

In some examples, terminal 102 can communicate, e.g., via a first accessnetwork 104 or a second access network 106. A single-connectivity (orsingle-radio, SR) terminal 102 can communicate via one access network104, 106 at a time. A dual-connectivity (dual-radio, DR) terminal 102can communicate concurrently via both access network 104 and accessnetwork 106, as shown by the stippled lines. Some examples herein relateto DR terminals 102. In some examples, a single access network includesthe illustrated components of access networks 104 and 106. In someexamples, operations described herein are performed with respect to eachaccess network 104, 106 as though a DR terminal 102 were two separateterminals, one attached to each access network 104, 106. In someexamples, operations described herein are performed with reference toeach access network as though a DR terminal 102 were attached to onlyone access network 104, 106.

In the illustrated example, first access network 104 includes a firstentry node 108, e.g., a 5G gNodeB, and a first access node 110, e.g., a5G Access and Mobility Management Function (AMF) or User Plane Function(UPF). Second access network 106 includes a second entry node 112, e.g.,an LTE eNodeB, and a second access node 114, e.g., an LTE mobilitymanagement entity (MME), serving gateway (SGW), or public/packet datanetwork (PDN) gateway (PGW). Other examples of access nodes include aGSM mobile switching center (MSC) server (MSS). For brevity herein, theterm “entry node” refers to a gNodeB, eNodeB, RNC, WIFI access point(AP), or other network device that is the initial node that terminal 102communicates with in order to access the services of a correspondingaccess network. Terminal 102 can communicate via the respective entrynodes 108, 112 with the respective access nodes 110, 114. In someexamples, the first access network 104 may provided packet-switchedconnections and the second access network 106 may providecircuit-switched connections. In some examples, the first access network104 may be a packet-switched cellular type of access network and thesecond access network 106 may be a packet-switched local-area-networktype of access network.

A nonlimiting example EN-DC configuration is shown using dashed lines.Entry node 112, e.g., an eNodeB, serves as the master node, and entrynode 108, e.g., a gNodeB, serves as the secondary node. Entry node 112communicates with access node 114 over an S1 interface for both thecontrol plane and the user plane. Entry node 108 communicates with entrynode 112 over an X2-C interface for the control plane, and with at leastone of access nodes 110, 114 over an S1-U interface for the user plane.In some EN-DC configurations, the user plane from first entry node 108passes through access node 114, e.g., an SGW or PGW, via the illustratedS1-U interface, and access node 110 is not used.

In some examples, LTE and NR services are offered concurrently within aparticular radio band or frequency allocation using the EN-DCconfiguration. Entry nodes 108 and 112 exchange messages, e.g.,including X2 Application Protocol (X2AP) Information Elements (IEs) suchas EN-DC Resource Configuration, MeNB Resource Coordination Information,or SgNB Resource Coordination Information IEs, to prevent interferencedue to overlapping LTE and NR transmissions.

The terminal 102 can be configured to initiate or receive acommunication session, such as a voice call, a video call, or anothersort of synchronous communication. Initiation of such communications mayinvolve communication clients and Session Initiation Protocol (SIP, RFC3261) clients communicatively connected with components of thetelecommunications network, e.g., session-control node 116. In variousembodiments, the session-control node 116 represents components of anInternet Protocol (IP) Multimedia Subsystem (IMS) core network.Session-control node 116 can be part of an application network 118,e.g., an IMS network or other network providing services to terminal102. Application network 118 can also be referred to as an “upper-level”network that uses the services provided by access networks 104, 106 tocommunicate with terminals 102. Network 100 can include or be connectedwith any number of access networks 104, 106 or any number of applicationnetworks 118. The first access node 110 and the second access node 114are examples of access nodes or devices that can control or modifycommunications between application network 118 and terminal 102 viaaccess network(s) 104 or 106.

Each of the entry nodes 108, 112, the access nodes 110, 114, and thesession-control node 116, may be, include, or be implemented at leastpartly using a server or server farm, multiple, distributed serverfarms, a mainframe, a work station, a PC, a laptop computer, a tabletcomputer, an embedded system, or any other sort of device or devices. Inone implementation, one or more of first access node 110, the secondaccess node 114, and the session-control node 116 may represent aplurality of computing devices working in communication, such as acloud-computing node cluster. Also, the first access node 110, thesecond access node 114, and the session-control node 116 may each be orinclude nodes or devices of a telecommunications network. Examples ofsuch components are described below with reference to FIG. 2 .

In some examples, entry nodes 108 and 112 are communicatively connectedto each other via a coordination channel 120, e.g., an EN-DC X2 or X2-Cinterface. This can permit entry nodes 108 and 112 to share data aboutthe load on the respective access networks 104, 106, and to coordinatetheir operations. For example, entry nodes 108 and 112 can be embodiedin a common set of computing hardware (e.g., as noted in the previousparagraph), and can communicate via inter-process communication (IPC)techniques such as signals, pipes, sockets, or shared memory, orinter-virtual-machine (inter-VM) sockets or other inter-VM communicationtechniques. Additionally or alternatively, entry nodes 108 and 112 canbe arranged to intercommunicate with each other, e.g., directly (via aphysical cable connection) or via a logically-direct connection (e.g.,via a virtual private network, VPN, or tunnel connection running over anetwork). In some examples, entry nodes 108 and 112 are installed at acommon co-location facility and are communicatively connected withinthat facility. Other nodes or sets of nodes can additionally oralternatively be connected using coordination channels.

Data can be sent between the terminal 102 and an entry node 108, 112 inradio frames, each having multiple subframes. In some examples, oneradio frame can have a duration of ten milliseconds, and include tendistinct subframes, each having a duration of one millisecond. Thesubframes can each be identified by a subframe number. For example, asingle radio frame can include ten subframes identified as subframe 0,subframe 1, . . . , and subframe 9. An entry node 108, 112 can sendRadio Resource Control (RRC) messages to attached terminals 102 in atleast some of the radio frames, e.g., indicating the radio-frame formator transmission mode in use.

A terminal 102 can send data to the appropriate entry node 108, 112including signal quality measurements or other channel conditioninformation (CCI). CCI can indicate how well the terminal 102 isreceiving data from the entry node 108, 112. For example, CCI caninclude indications of received signal quality and/or received signalstrength at terminal 102, or values derived from those indications.Example CCI values can include a channel quality indicator (CQI), asignal to interference and noise ratio (SINR), or any other signalquality metric.

Terminals 102 and entry nodes 108, 112 can be configured to supportmultiple transmission modes at the physical layer, such as transmissionmodes defined by 3GPP standards. Examples of such transmission modesinclude TM2, TM3, TM4, TM9, and TM10. Throughout this document,reference is made to TM4 and TM9 for clarity of illustration. In atleast some examples, other transmission modes can be used in place ofTM4 or TM9. In some cases, the transmission modes a terminal 102 orentry node 108, 112 supports can depend in part on the number ofantennas that device can use to send or receive data. For example, TM4can be used for closed-loop spatial multiplexing for transmissions bymultiple-input multiple-output (MIMO) devices with multiple antennas.TM9 can also be used for spatial multiplexing at up to eight layers bysome MIMO devices.

Some transmission modes can provide greater throughput from an entrynode 108, 112 to a terminal 102 in certain situations. For example, insome cases TM9 can provide a throughput improvement of approximately 15%percent for terminals 102 near the edge of a cell compared to TM4, whileTM4 can provide a throughput improvement of approximately 10% over TM9for “mid-cell” terminals 102 closer to the entry node 108, 112 and athroughput improvement of approximately 30% over TM9 for “near-cell”terminals 102 that are very close to the entry node 108, 112. An entrynode 108, 112 can accordingly choose one of the multiple transmissionmodes it supports for a particular terminal 102 based on the CCIreported by that terminal 102. For example, if a terminal 102 reportslow signal quality, it may indicate that the terminal 102 is on the edgeof the cell, and the entry node 108, 112 can respond by selecting TM9.However, if the terminal 102 reports higher signal quality, it mayindicate that the terminal 102 is at “mid-cell” or “near-cell,” and theentry node 108, 112 can respond by selecting TM4.

An entry node 108, 112 can select the transmission mode to use for aterminal 102 for every group of one or more radio frames. For example,an entry node 108, 112 can continue using a previous transmission modeor change to a different transmission mode at every radio frame, atevery ten radio frames, or at intervals corresponding to any othernumber of radio frames.

As used herein, a message “sent to,” “transmitted to,” or “transmittedtoward” a destination, or similar terms, can be sent directly to thedestination, or can be sent via one or more intermediate network nodesor devices to the destination. Those intermediate network nodes ordevices can include access nodes 110, 114. Similarly, a message“received from” a destination can be received directly from thedestination, or can be received via one or more intermediate networknodes or devices from the destination. A message passing through one ormore intermediate network nodes or devices can be modified by thosenetwork nodes or devices, e.g., by adding or removing framing, or bychanging a presentation of at least part of the message, e.g., from aSIP start-line to a SIP header or vice versa. As used herein, a “reply”message is synonymous with a “response” message. The term “reply” isused for clarity, e.g., when discussing reply messages sent in responseto the receipt of messages.

FIG. 2 is a block diagram illustrating a system 200 permittingradio-resource management according to some implementations. The system200 includes a terminal 202, e.g., a wireless phone or other terminalsuch as a terminal 102, FIG. 1 , coupled to a server 204 via a network206. The server 204 can represent an entry node 108, 112, an access node110, 114, or another control device or information server of atelecommunications network.

The network 206 can include one or more networks, such as a cellularnetwork 208 and a data network 210. In some examples, network 206 mayinclude any network configured to transport IP packets, e.g., IPv4,IPv6, or any future IP-based network technology or evolution of anexisting IP-based network technology. For example, the network 206 caninclude one or more core network(s) connected to terminal(s) via one ormore access network(s).

Terminal 202 can include one or more computer readable media (CRM) 212,such as memory (e.g., random access memory (RAM), solid state drives(SSDs), or the like), disk drives (e.g., platter-based hard drives),another type of computer-readable media, or any combination thereof.Terminal 202 can include one or more processors 214 configured toexecute instructions stored on CRM 212. The CRM 212 can be used to storedata and to store instructions that are executable by the processors 214to perform various functions as described herein. The CRM 212 can storevarious types of instructions and data, such as an operating system,device drivers, etc. The processor-executable instructions can beexecuted by the processors 214 to perform the various functionsdescribed herein.

The CRM 212 can be or include computer-readable storage media.Computer-readable storage media include, but are not limited to, RAM,ROM, EEPROM, flash memory or other memory technology, CD-ROM, digitalversatile disks (DVD) or other optical storage, magnetic cassettes,magnetic tape, magnetic disk storage or other magnetic storage devices,or any other tangible, non-transitory medium which can be used to storethe desired information and which can be accessed by the processors 214.Tangible computer-readable media can include volatile and nonvolatile,removable and non-removable media implemented in any method ortechnology for storage of information, such as computer readableinstructions, data structures, program modules, or other data.

Processor(s) 214 can include, e.g., one or more processor devices suchas central processing units (CPUs), microprocessors, microcontrollers,field-programmable gate arrays (FPGAs), application-specific integratedcircuits (ASICs), programmable logic devices (PLDs), programmable logicarrays (PLAs), programmable array logic devices (PALs), or digitalsignal processors (DSPs). For brevity, processor 214 and, if required,CRM 212, are referred to for brevity herein as a “control unit.” Forexample, a control unit can include a CPU or DSP and instructionsexecutable by that CPU or DSP to cause that CPU or DSP to performfunctions described herein. Additionally or alternatively, a controlunit can include an ASIC, FPGA, or other logic device(s) wired(physically or via blown fuses or logic-cell configuration data) toperform functions described herein. Other examples of control units caninclude processor 230 and, if required, CRM 232, discussed below.Accordingly, functions described as carried out by processor(s) 214 inresponse to instructions stored on a CRM 212 can additionally oralternatively be performed by a control unit configured to performfunctions described herein without reading instructions to do so fromCRM 212.

Terminal 202 can further include a user interface (UI) 216, e.g.,including an electronic display device, a speaker, a vibration unit, atouchscreen, or other devices for presenting information to a user andreceiving commands from the user, e.g., under control of processor(s)214. Terminal 202 can further include one or more network interface(s)218 configured to selectively communicate (wired or wirelessly) via thenetwork 206, e.g., via an access network 104 or 106, under control ofthe processor(s) 214.

CRM 212 can include processor-executable instructions of a clientapplication 220 and a detection module 222. The client application 220,e.g., a native or other dialer, can permit a user to originate andterminate communication sessions associated with the terminal 202, e.g.,a wireless phone. The client application 220 can additionally oralternatively include an SMS, RCS, or presence client, or a client ofanother telephony service offered by the server 204. The clientapplication 220 can additionally or alternatively include an app a Webbrowser configured to communicate via WebRTC or other non-3GPPprotocols.

CRM 212 can additionally or alternatively store processor-executableinstructions of a physical-layer (“PHY”) module 224. PHY module 224 canperform PHY functions such as those described in 3GPP 36.211, 36.213,38.300, 38.411, 38.413, or other LTE or NR PHY standards. In someexamples, some of the PHY functions are performed by dedicated logic orhardware or firmware (e.g., implemented in an FPGA or ASIC), representedas PHY unit 226. Some examples include at most one of PHY module 224 andPHY unit 226, while other examples include both PHY module 224 and PHYunit 226.

In some examples, server 204 can communicate with (e.g., iscommunicatively connectable with) terminal 202 or other devices via oneor more communications interface(s) 228, e.g., network transceivers forwired or wireless networks, or memory interfaces. Example communicationsinterface(s) 228 can include ETHERNET or FIBRE CHANNEL transceivers,WIFI radios, or DDR memory-bus controllers (e.g., for DMA transfers to anetwork card installed in a physical server 204).

The server 204 can include one or more processors 230 and one or moreCRM 232. The CRM 232 can be used to store processor-executableinstructions of an allocation module 234 and a rate module 236. Theprocessor-executable instructions can be executed by the one or moreprocessors 230 to perform various functions described herein, e.g., withreference to FIGS. 3-8 . In some examples, server 204 can be configuredto, e.g., by executing the processor-executable instructions, performfunctions described herein with reference to FIGS. 3-8 . In someexamples, at least one of communications interface 228 or processor 230can include components to perform, or otherwise be configured toperform, PHY functions, e.g., as discussed above with respect to PHYmodule 224 or PHY unit 226.

Example cellular networks 208 can include a GSM or UMTS network; auniversal terrestrial radio network (UTRAN) or an GSM Enhanced Datarates for GSM Evolution (EDGE) radio access network (GERAN); an evolveduniversal terrestrial radio access network (E-UTRAN) (e.g., LTE); a 3GPP5G access network (e.g., NR running in non-standalone, NSA, orstandalone, SA, mode); an Evolution-Data Optimized (EVDO), Advanced LTE(LTE+), Generic Access Network (GAN), Unlicensed Mobile Access (UMA),GPRS, EDGE, Advanced Mobile Phone System (AMPS), High Speed PacketAccess (HSPA), or evolved HSPA (HSPA+) network.

In some examples, cellular network 208 can include a base station (e.g.,an eNodeB or gNodeB), a radio network controller (RNC) (e.g., for UMTSaccess networks), or other elements. A cellular network 208 or awireless data network 210 may use any sort of air interface, such as acode division multiple access (CDMA), time division multiple access(TDMA), frequency division multiple access (FDMA), or orthogonalfrequency division multiple access (OFDMA) air interface.

Example data networks 210 can include a WIFI (IEEE 802.11), BLUETOOTH(IEEE 802.15.1), or other LAN or PAN access networks, e.g., in the IEEE802.1* family, a satellite or terrestrial wide-area access network suchas a wireless microwave access (WIMAX) network, a wired network such asthe PSTN, an optical network such as a Synchronous Optical NETwork(SONET), or other fixed wireless or non-wireless networks such asAsynchronous Transfer Mode (ATM) or Ethernet.

In some examples, data network 210 (e.g., a non-cellular network) cancarry voice traffic using VoIP or other technologies as well as datatraffic, or cellular network 208 can carry data packets using High SpeedPacket Access (HSPA), LTE, or other technologies, as well as voicetraffic. Similarly, in some examples, cellular network 208 can carrydata traffic as well as voice traffic. For example, many LTE and NRnetworks carry both data and voice in a PS format, e.g., according tothe voice-over-LTE (VoLTE) standard for PS voice.

The network 206 may also include a number of devices or nodes notillustrated in FIG. 1 or 2 . Nonlimiting examples of such devices ornodes include an Access Transfer Gateway (ATGW), a serving GPRS supportnode (SGSN), a gateway GPRS support node (GGSN), a policy control rulesfunction (PCRF) node, a session border controller (SBC), or anon-3GPP-access interworking function (N3IWF). Similarly, throughoutthis disclosure, other nodes or devices can be used in conjunction withlisted nodes or devices. For example, a telecommunications network caninclude many core network nodes or devices, only some of which implementfunctions described herein for core network nodes or devices.

Illustrative Operations

FIG. 3 is a dataflow diagram illustrating an example process 300 forallocating radio resources, and related data items. FIG. 3 also shows anexample radio frame 302 comprising a plurality of subframes 304. Process300 can be performed, e.g., by a control unit of a network base station,e.g., a control unit of the server 204 (for example, an entry node 108,112). In some examples, the control device includes one or moreprocessors (e.g., processor 230) configured to perform operationsdescribed below, e.g., in response to computer program instructions ofthe allocation module 234. In some examples, the network base stationcan include a communications interface 228 configured to communicatewirelessly with one or more terminals 102, 202 of the network 100, 206.

Operations shown in FIG. 3 and in FIGS. 4-10 , discussed below, can beperformed in any order except when otherwise specified, or when datafrom an earlier step is used in a later step. For clarity ofexplanation, reference is herein made to various components shown inFIGS. 1-2 that can carry out or participate in the steps of the examplemethod, and to various operations and messages that can occur or betransmitted while the example method is carried out or as part of theexample method. It should be noted, however, that other components canbe used; that is, example method(s) shown in FIGS. 3-10 are not limitedto being carried out by the identified components, and are not limitedto including the identified operations or messages.

At 306, the control unit can select, for each of the one or moreterminals, a respective downlink transmission mode (DTM) 308 based atleast in part on respective channel condition information (CCI) 310.Example DTMs can include 3GPP TM4 or TM9. CCI 310 can indicate orrepresent properties of the RF environment along path(s) taken betweenthe base station and a terminal 102. Such properties can include, e.g.,propagation delay, multipath characteristics, fading (includingfrequency-sensitive fading), attenuation, or phase shifts. Example formsof CCI 310 described in 3GPP 36.213 v13.3.0 § 7.2 can include, a ChannelQuality Indicator (CQI), a precoding matrix indicator (PMI), a precodingtype indicator (PTI), a CSI-RS resource indicator (CRI), a rankindication (RI), or a beam index (e.g., for FD-MIMO). In some examples,the control unit can select the DTM 308 based at least in part on, orbased exclusively on, an uplink SINR measured by the network basestation (e.g., an eNB).

The control unit can select which DTM 308 to use for a terminal's datain one or more radio frames based on signal quality metrics reported bythe terminal, e.g., in or as CCI 310. For example, a terminal may reportthat it is receiving data from the base station at a relatively highersignal quality, which often occurs when the terminal is relativelycloser to the base station and is considered to be “near-cell” or“mid-cell.” In this situation, the control unit may choose to use TM4for the terminal's data in the next radio frame. However, if theterminal reports that it is receiving data at a relatively lower signalquality, which can often occur if the terminal is located relativelyfarther from the base station (e.g., at the edge of a cell), the controlunit may instead choose to use TM9 for the terminal's data in the nextradio frame, because TM9 can often lead to higher throughput at the celledge than TM4.

In some examples, the respective DTMs can be selected from apredetermined set 312 of DTMs (“Downlink Transmission Mode Library”).Set 312 can include at least one DTM 308, or a plurality of DTMs 308.The set 312 of DTMs can include, e.g., only DTMs supported by particularterminal(s) 102 that are connected to the base station. In someexamples, the set 312 of DTMs 308 includes or consists of TM4 and TM9.

In some examples, e.g., some EN-DC deployments, the DTMs 308 areassociated with respective, different types of access network. Forexample, LTE can be associated with TM9 and another type of accessnetwork with TM4, or vice versa. In some of these examples, operation306 can include selecting a common DTM 308 for all the terminals. Forexample, operation 306 can include selecting, at an eNodeB, TM9 (or TM4)as the DTM 308 for all terminals attached to the eNodeB. Additionally oralternatively, operation 306 can include selecting, at a gNodeB, TM4 (orTM9) as the DTM 308 for all terminals attached to the gNodeB.

At 314, the control unit can determine a subframe allocation 316 basedat least in part on the selected DTMs 308 of the predetermined set 312of DTMs. The subframe allocation 316 can indicate exactly one DTM 308 ofthe predetermined set 312 of DTMs for each of a plurality of thesubframes 304 of the radio frame 302. In the illustrated example,subframes 304 numbers 1, 2, 6, and 7 (shown hatched) are associated bysubframe allocation 316 with a first DTM 308, e.g., TM9, and remainingsubframes 304 numbers 0, 3, 4, 5, 8, and 9 are associated with a second,different DTM 308, e.g., TM4. In some examples, frame 302 includes tensubframes 304, and subframe allocation 316 can assign between zero andsix of the ten subframes 304 as MBSFN subframes.

At 318, the control unit can transmit downlink data 320 to at least oneof the one or more terminals 102 using the communications interface 228based at least in part on the subframe allocation 316. For example, thecontrol unit can transmit at least some of the downlink data 320 usingthe first DTM 308 in subframes 304 numbers 1, 2, 6, and 7, or cantransmit at least some of the downlink data 320 using the second DTM 308in subframes 304 numbers 0, 3, 4, 5, 8, and 9. Data can be transmitted,e.g., as in the standards for LTE, NR, WIFI, or other access network(s)104, 106 (e.g., on an LTE or NR PDSCH). In some examples, downlink data320 is transmitted on a PDSCH within an MBSFN subframe, e.g., using TM9or other transmission modes. In some examples, the hatched subframes areMBSFN subframes. In some examples, downlink data 320 includes or isassociated with control information, e.g., transmitted on a PDCCH. PDSCHdata and corresponding PDSCH information can be transmitted in the samesubframe or in different subframes.

In some examples, the network base station (e.g., entry node 108 or 112)includes a full-dimension multiple-input multiple-output (FD-MIMO)antenna array connected with the communications interface 228. TheFD-MIMO antenna array can include, e.g., one or more two-dimensionalarrays of antennas, spaced apart or overlaid. Each two-dimensional arrayof antennas can be associated with a respective, different polarizationof electromagnetic radiation emitted by that array of antennas. FD-MIMOantennas can permit beamforming in both azimuthal and elevationaldirections. Accordingly, in some examples, operation 318 can includetransmitting at least some of the downlink data 320 to a first terminal102 of the one or more terminals in a formed beam using the FD-MIMOantenna array. In some examples using TM9 FD-MIMO for LTE, 16×2 or 32×2MU-MIMO configurations can be used.

At least one example has at least some of, or all of, thecharacteristics and features given in this paragraph. The predeterminedset 312 of DTMs consists of 3GPP Transmission Mode Four and 3GPPTransmission Mode Nine. The subframe allocation 316 indicates a firstsubset (e.g., subset 514, FIG. 5 ) of the plurality of subframes and asecond, disjoint subset (e.g., subset 516, FIG. 5 ) of the plurality ofsubframes. The subframe allocation assigns the subframes of the firstsubset as Multimedia Broadcast Multicast Service (MBMS) Single FrequencyNetwork (MBSFN) subframes associated with Transmission Mode Nine. Thesubframe allocation assigns the subframes of the second subset asnon-MBSFN subframes associated with Transmission Mode Four.

FIG. 4 is a dataflow diagram illustrating example processes 400 forallocating radio resources, and related data items. Processes 400 can beperformed, e.g., by a control unit of network base station or otherserver 204, e.g., in response to computer program operations of theallocation module 234. In some examples, operation 402 can precedeoperation 306. In some examples, operation 428 can follow operation 306.In some examples, operation 404 can be performed as part of, in parallelwith (as shown), or after operation 318. In some examples, operation 412can be performed in parallel with or after (as shown) operation 318,after operation 404, or after both operation 318 and operation 404.

At 402, the control unit can receive, using the communications interface228, the respective channel condition information 310 for at least oneof the one or more terminals 102. For example, the control unit canreceive the CCI via a transmission on the PUSCH from a terminal 102.This can be done, e.g., as set forth in the 3GPP specifications foruplink data transmission. In some examples, unlike the 3GPPspecifications, uplink data is transmitted during an MBSFN subframe,e.g., using TM9 or another transmission mode indicated in the subframeallocation 316.

At 404, the control unit can transmit a terminal-specific referencesignal 406 to a first terminal 408 (shown in phantom) of the one or moreterminals using the communications interface based at least in part onthe subframe allocation 316. Operation 404 can be performed as part of,or (as shown) in parallel with operation 318. For example, theterminal-specific reference signal 406 can be a CSI-RS transmittedduring a subframe indicated in the subframe allocation 316 as using aDTM 308 such as TM9.

In some examples, represented with stippled lines, the first subframeallocation 316 includes an assignment of a first subframe 410 of theplurality of subframes 304. In some of these examples, the control unitcan transmit the terminal-specific reference signal 406 during the firstsubframe 410. For example, the first subframe 410 can be as an MBSFNsubframe associated with TM9, and the terminal-specific reference signal406 can be a CSI-RS signal.

At 412, the control unit can receive, subsequent to operation 404,second CCI 414 associated with the terminal-specific reference signal406. In some examples, second CCI 414 can be associated with the sameDTM 308, 3GPP LTE/NR antenna port, or other transmission parameter as isthe CCI 310 associated with terminal 408. For example, CCI 310 caninclude a first CRI determined at terminal 408 based on a first CSI-RS,and second CCI 414 can include a second CRI determined at terminal 408based on a second CSI-RS, namely the terminal-specific reference signal406.

At 416, the control unit can select a second DTM 418 for the firstterminal 408 based at least in part on the second CCI 414. In someexamples, as terminal 408 moves toward the network base station, TM4 maybecome more desirable. Therefore, the control unit may select TM9 as theDTM 308 for that terminal, and later select TM4 as the second DTM 418for that terminal. In other examples, as terminal 408 moves away fromthe network base station, TM9 may become more desirable (e.g., asindicated by lower quality reports in a CQI sent using TM4 with RI=1).Therefore, the control unit may select TM4 as the DTM 308 for thatterminal, and later select TM9 as the second DTM 418 for that terminal.

At 420, the control unit can determine a second subframe allocation 422based at least in part on the second DTM 418. Examples are discussedherein, e.g., with reference to operation 314.

In some examples in which the first subframe 410 is assigned by thefirst subframe allocation 316 to TM9, the control unit can determine thesecond subframe allocation 422 assigning the first subframe 410 as anon-MBSFN subframe associated with TM4. In some examples in which thefirst subframe 410 is assigned by the first subframe allocation 316 toTM4, the control unit can determine the second subframe allocation 422assigning the first subframe 410 as an MBSFN subframe associated withTM9. This can permit more effectively balancing load between TM4 and TM9users, and can reduce latency that would otherwise be incurred byswitching DTM per frame 302 rather than per subframe 304.

At 424, the control unit can transmit second downlink data 426 to thefirst terminal 408 using the communications interface 228 based at leastin part on the second subframe allocation 422. Examples are discussedherein, e.g., with reference to operation 318. As discussed above,second downlink data 426 can include or be associated with controlinformation.

At 428, in some examples, the control unit can transmit a controlmessage, e.g., a Radio Resource Control (RRC) reconfiguration message(e.g., RRCConnectionReconfiguration) or other message, to the terminal102. The reconfiguration message can tell the terminal 102 whichtransmission mode to use when interpreting data in subsequent radioframe(s) 302. RRC messages are sent in data packets according to thePacket Data Convergence Protocol (PDCP), and are interpreted by terminal102 at the network layer. Accordingly, when an RRC message indicates achange to the transmission mode, the terminal 102 can process the RRCmessage at the network layer to discover the change and then passinformation about the new transmission mode through the medium accesscontrol (MAC) layer to the physical layer (e.g., PHY module 224 or PHYunit 226) so that received radio frames 302 can be interpreted at thephysical layer using the correct transmission mode. Operation 428 can beperformed after selecting the DTM 308, e.g., when the control unitchanges the DTM 308 it is using for a particular terminal 102.Additionally or alternatively, operation 428 can be performedperiodically on a schedule.

FIG. 5 is a dataflow diagram illustrating example processes 500 forallocating radio resources, and related data items. Processes 500 can beperformed, e.g., by a control unit of network base station or otherserver 204, e.g., in response to computer program operations of theallocation module 234 (e.g., operations 502-512) or the rate module 236(e.g., operations 520-532). In some examples, operation 314 can includeoperation 510. In some examples, operation 318 can be followed byoperation 532.

In some examples, the network base station is associated with a firstaccess network of a first type, e.g., access network 104 or 106. Variousexamples permit load-balancing between access networks, e.g., in aco-channel spectrum coexistence scenario such as EN-DC. Various examplesprovide time-division multiplexing between access networks sharing aspectrum allocation. In some examples, the network base station iscommunicatively connectable with a second base station associated with asecond access network of a second, different type.

For example (e.g., in some EN-DC configurations such as those shown inFIG. 1 ), the base station can be entry node 112, the first accessnetwork can be access network 106, the second base station can be entrynode 108, and the second access network can be access network 104.Alternatively, the base station can be entry node 108, the first accessnetwork can be access network 104, the second base station can be entrynode 112, and the second access network can be access network 106. Insome examples, the first and second types can be, respectively, one of:LTE and NR, NR and LTE, CS and PS, PS and CS, 3GPP and non-3GPP,non-3GPP and 3GPP, or combinations thereof.

At 502, the control unit can send a request 504 for second-network loadinformation 506 to the second base station. Operation 502 can beperformed before operation 508, in some examples. For example, thesecond base station can transmit second-network load information 506 inresponse to request 504 in addition to or instead of spontaneously.

At 508, the control unit can receive, from the second base station, thesecond-network load information 506 of the second access network. Insome examples, the second base station can be configured to transmit thesecond-network load information 506 periodically, substantiallyperiodically, or on demand. In some examples using operation 502 andoperation 508, the second-network load information 506 can be receivedin response to request 504. In some examples not using operation 502,the second-network load information 506 can be received after beingspontaneously transmitted by the second base station, e.g., on aschedule.

In various examples, the base station can send the request 504, or thesecond base station can send the second-network load information 506, inresponse to load or load changes meeting predetermined criteria. Forexample, if the load on the first access network significantly increasesor decreases, rises above a first threshold, or falls below a secondthreshold, the control unit can send the request 504 to adapt traffic onthe second access network to the changed conditions, or vice versa.Additionally or alternatively, the base station can send the request504, or the second base station can send the second-network loadinformation 506, periodically (e.g., substantially on a defined scheduleor at predefined time intervals), or on request of the base station, thesecond base station, or a common controller.

In some examples, operation 508 can include receiving the second-networkload information 506 via an X2 interface, e.g., the X2-C interface shownin FIG. 1 , or another coordination channel 120. The second-network loadinformation 506 can be carried in IEs defined by X2AP, e.g., any of theIEs that can be carried as part of an X2AP Load Information message(3GPP 36.423 v15.2.0 § 8.3.1), or in other IEs. In some examples, thesecond-network load information 506 can indicate or represent the numberof terminals 102 attached to the second base station. Additionally oralternatively, the second-network load information 506 can indicate orrepresent the number of terminals 102 attached to the second basestation that meet any of the following criteria, or the proportion ofthe terminals 102 attached to the second base station that meet any ofthe following criteria: attached via a particular network technology(e.g., LTE or NR); having CCI indicating that use of a particular DTMwould be preferred (e.g., indicating that TM4 would be preferred, suchas may be the case for a terminal 102 relatively closer to thesecond-network base station, or indicating that TM9 would be preferred,such as may be the case for a terminal 102 relatively farther from thesecond-network base station); or having a location (e.g.,GPS-determined, triangulated, or range based on round-trip time, RTT)with respect to the second base station indicating that use of aparticular DTM would be preferred. CCI or location can be mapped to anindication of a DTM preference, e.g., using a stored lookup tableprovisioned in the second base station and having empirically-determinedvalues. Additionally or alternatively, the second-network loadinformation 506 can indicate or represent the amount of traffic on thesecond access network, e.g., in bits per second, resource blocksallocated per second, a percentage of a cap of either of those, or othernetwork-utilization measures. Second-network load information 506 caninclude instantaneous or smoothed values for any of the foregoing datavalues, e.g., arithmetic or exponentially-weighted moving averages, orwindowed sums, over a predetermined time period (e.g., 1 min or 5 min).

At 510, the control unit can determine the subframe allocation 316 basedat least in part on the second-network load information 506. Thesubframe allocation 316 can indicate, for each subframe 304 of theplurality of subframes in the frame 302, whether that subframe 304 isassociated with the first access network or the second access network.For example, LTE can be assigned to MBSFN subframes or to non-MBSFNsubframes. In some examples using operation 510, operation 306 caninclude selecting a single DTM 308 for at least some of, or all of, theterminals 102 attached to the network base station. For example, TM9 canbe assigned to all LTE terminals, TM4 to all NR terminals, or TM4 to allLTE terminals. In other examples, some subframes assigned to the firstaccess network can use a first DTM 308 and other subframes assigned tothe first access network can use a second, different DTM 308, orlikewise for the second access network. For example, some LTE subframes304 within a frame 302 can be TM4 and others can be TM9, or some NRsubframes 304 within a frame 302 can be TM4 and others can be TM9, orboth. This can permit both load-balancing between two access networksand using network capacity effectively depending on the spatialdistribution of terminals 102 attached to a particular network basestation.

At 512, the control unit can transmit at least a portion of the subframeallocation 316 to the second base station, e.g., via an X2 or X2-Cinterface. For example, the control unit can transmit the entiresubframe allocation 316, or less than the entire subframe allocation316. In some examples, operation 512 includes transmitting at leastthose portions of the subframe allocation 316 indicating which subframesare available for use by the second access network, or at least portionsof the subframe allocation 316 that are sufficient to permit the secondbase station to reliably determine which subframes are available for useby the second access network (e.g., transmitting the total number ofsubframes, plus identifiers of the subframes in used by the first accessnetwork). This permits each of the first base station and the secondbase station to schedule transmissions only in subframes assigned to thecorresponding access network, which can reduce interference and permitco-channel spectrum coexistence between, e.g., LTE and NR.

In some examples, the subframe allocation 316 indicates a first subset514 of the plurality of subframes 304 and a second, disjoint subset 516of the plurality of subframes 304. The subframe allocation 316 caninclude additional subframes that are part of neither the first subset514 nor the second subset 516 in some examples. In other examples, eachsubframe 304 of the frame 302 can be a member of exactly one of thesubsets 514, 516. The first subset 514 can be associated with apredetermined DTM 518 of the predetermined set 312 of DTMs. For example,the first subset 514 can be MBSFN subframes and the second subset 516non-MBSFN subframes, or vice versa.

At 520, in some of these examples, the control unit can determine afirst proportion 522 of traffic being carried by the network basestation that is first traffic 524. The first traffic 524 can beguaranteed bit-rate (GBR) traffic and can be associated with thepredetermined DTM 518. For example, the first traffic 524 can be VoLTEor ViLTE traffic using TM9 (or TM4). Examples are discussed below, e.g.,with reference to operation 602.

At 526, the control unit can determine, based at least in part on thefirst proportion 522, a first rate 528 of transmission of referencesignals 530 associated with the predetermined DTM 518 (e.g., CSI-RS, forDTM 518 as TM9). Examples are discussed below, e.g., with reference tooperation 610.

At 532, the control unit can transmit the reference signals 530associated with the predetermined DTM 518 (connection shown stippledsolely for clarity of the drawing) substantially at the first rate 528and during one or more subframes 304 of the first subset 514. Examplesare discussed below, e.g., with reference to operation 616.

FIG. 6 is a dataflow diagram illustrating an example process 600 forcontrolling the transmission of reference signals, and related dataitems. Process 600 can be performed, e.g., by a control unit of anetwork base station, e.g., a control unit of the server 204 (forexample, an entry node 108, 112). In some examples, the control deviceincludes one or more processors (e.g., processor 230) configured toperform operations described below, e.g., in response to computerprogram instructions of the rate module 236. In some examples, thenetwork base station can include a communications interface 228configured to communicate wirelessly with one or more terminals 102, 202of the network 100, 206.

At 602, the control unit can determine a first proportion 604 of trafficbeing carried by the network base station that is first traffic 606. Thefirst traffic 606 can be guaranteed bit-rate (GBR) traffic, can beassociated with terminals communicating with the network base stationusing a predetermined downlink transmission mode (DTM) 608 (e.g., TM9 orTM4), or both. The first proportion 604 can be a proportion of thenumber of attached terminals 102, the number of subframes being used perunit time (e.g., per radio frame), the number of bits being transferredper unit time (e.g., bits per second), or other traffic or load metrics.

At 610, the control unit can determine, based at least in part on thefirst proportion 604, a first rate 612 of transmission of referencesignals 614 associated with the predetermined DTM 608. For example, therate can be one transmission of reference signals 614 every r ms, rbeing from about 5 ms to about 60 ms. In some examples, e.g., in whichthe predetermined DTM 608 is TM9, the reference signals associated withthe predetermined DTM 608 can be CSI-RS signals.

At 616, the control unit can transmit the reference signals associatedwith the predetermined DTM 608 substantially at the first rate 612 andduring one or more subframes 618 associated with the predetermined DTM608. This can be done, e.g., as specified by the standards for thepertinent access network 104, 106. In some examples, the control unitcan transmit CSI-RS or DMRS reference signals during MBSFN subframesassociated with TM9 as the predetermined DTM 518.

FIG. 7 is a dataflow diagram illustrating example processes 700 forcontrolling the transmission of reference signals, and related dataitems. Processes 700 can be performed, e.g., by a control unit ofnetwork base station or other server 204, e.g., in response to computerprogram operations of the rate module 236. In some examples, operation702 can be performed after operation 610 or 616, e.g., after determiningthe first rate 612.

At 702, the control unit can determine a second proportion 704 oftraffic being carried by the network base station that is first traffic606. Examples are discussed herein, e.g., with reference to operation602. In some examples, the first proportion 604 is higher than thesecond proportion 704. In some examples, operations 602 and 702represent successive instances in a sequence of proportiondeterminations, e.g., scheduled stochastically or at regular intervals.For example, a proportion 604, 704 can be determined about every pseconds, e.g., p=0.1. In some examples, p can be based on the number ofGBR bearers concurrently connected to the network base station.

At 706, the control unit can determine, based at least in part on thesecond proportion 704, a second rate 708 of transmission of referencesignals 614 associated with the predetermined DTM 608. Examples arediscussed herein, e.g., with reference to operation 610. In someexamples, the first rate 612 is higher than the second rate 708. Forexample, the rate can be positively correlated with (e.g., directlyproportional to, whether linearly, multiplicatively, or exponentially)the proportion of first traffic 606. As noted above, this can providemore accurate CCI (e.g., CCI 310) associated with GBR traffic, which canimprove the reception of data or reduce the required retransmission rateof packets, and thereby maintain GBR throughput. This can also provideincreased capacity for delay-tolerant traffic such as non-GBR traffic.In some examples, when the number of concurrently-connected GBR bearersdrops below a threshold, the network base station can update the firstrate 612 or the second rate 708.

At 710, the control unit can transmit the reference signals 614associated with the predetermined DTM 608 substantially at the secondrate 708 and during the one or more subframes 618 associated with thepredetermined DTM 608. Examples are discussed herein, e.g., withreference to operation 616.

FIG. 8 is a dataflow diagram illustrating example processes 800 forallocating radio resources and transmitting downlink data, and relateddata items. Processes 800 can be performed, e.g., by a control unit ofnetwork base station or other server 204, e.g., in response to computerprogram operations of the allocation module 234 or the rate module 236.In some examples, processing can begin with operation 802, 806, 810, or816. Some examples use operation 816 and omit operation 810. In someexamples, operation 616 can include, be followed by, or be performed inparallel with, operation 820. In some examples, at least one ofoperations 802, 806, 810, and 816 is performed before operation 616.

At 802, the control unit can transmit a first terminal-specificreference signal 804 (which can represent terminal-specific referencesignal 406) of the reference signals 614 to a first terminal in one ofthe one or more subframes associated with the predetermined DTM 608.Examples are discussed herein, e.g., with reference to operation 404.

At 806, the control unit can receive first CCI 808 from the firstterminal. The first CCI 808 can be associated with the firstterminal-specific reference signal 804. Examples are discussed herein,e.g., with reference to operations 402 and 412.

At 810, the control unit can select, for each of the plurality ofterminals attached to the network base station, a respective DTM 812(which can represent DTM 308) based at least in part on the channelcondition information (CCI) 808, or other respective CCI associated withthat terminal (e.g., as discussed herein with reference to CCI 310). Therespective DTMs 812 can be selected from a predetermined set 814 ofDTMs. Examples are discussed herein, e.g., with reference to operation306. The predetermined set 814 of DTMs can include the predetermined DTM608. Although shown separately for clarity of illustration, DTM 608 canbe one of the DTMs 812.

At 816, the control unit can determine a subframe allocation 818 (whichcan represent subframe allocation 316) based on information of aplurality of terminals attached to the network base station. Theplurality of terminals can include, e.g., at least some of, or all of,the terminals attached to the network base station. For example, theplurality of terminals can include only those terminals attached to thebase station that are using a particular DTM, e.g., TM4 or TM9 (e.g., inEN-DC configurations). The subframe allocation 818 can indicate, foreach of a plurality of subframes (e.g., subframes 304) of a radio frame(e.g., frame 302), exactly one DTM of the predetermined set 814 of DTMs.Moreover, the subframe allocation 818 can indicate the one or moresubframes associated with the predetermined DTM 608. Examples arediscussed herein, e.g., with reference to operation 314. In someillustrative network configurations, increasing the rate ofreference-signal transmission reduces the resources available for thePDSCH. In these configurations, the rate of transmission is increasedwhen more VoLTE (or other GBR) users (or bearers) are active thannon-realtime (or other non-GBR) users.

In some examples, the subframe allocation 818 indicates a first subsetof the plurality of subframes and a second, disjoint subset of theplurality of subframes. Examples are discussed herein, e.g., withreference to first subset 514 and second subset 516. The first subset514 can include the one or more subframes associated with thepredetermined DTM 608. The predetermined DTM 608 can be TM9. Thesubframe allocation 818 can assign the subframes of the first subset 514as MBSFN subframes associated with TM9. The subframe allocation 818 canalso assign the subframes of the second subset 516 as non-MBSFNsubframes. In some of these examples, the number of MBSFN subframes canbe controlled (operation 816) based on the number of TM9 terminals 102attached to the base station, and the rate of CSI-RS transmissions canbe controlled (operations 610, 706) based on the type of traffic to orfrom those TM9 terminals 102.

At 820, the control unit can transmit downlink data 822 (which canrepresent downlink data 320) to at least a first terminal of theplurality of terminals during a first subframe of the one or moresubframes associated with the predetermined DTM 608 based at least inpart on the subframe allocation 818. Examples are discussed herein,e.g., with reference to operation 318. Downlink data 822 can include orbe associated with control information, as discussed above.

As noted above, operations 616 and 820 can be performed in a coordinatedmanner. For example, during an MBSFN subframe, CSI-RS reference signals614 (operation 616) can be transmitted in the PDSCH along with DL data822 (operation 820), all using TM9.

Some examples of FIGS. 3-8 can use an algorithm such as that listed inTable 1.

TABLE 1 If (# of QCI1 users ≥ 40%) and (MBSFN allocated Subframes <40%): Wait 100 ms MBSFN+= 1 Send measurement report to NR NR Subframesscheduling −= 10% Else If #of QCI1 users<40% <= MBSFN allocatedSubframes: Wait 100 ms Send measurement report to NR NR Subframesscheduling += 10%

Other examples can use Table 1, except with at least one of (or all of)of the numeric values (e.g., the 100-ms time intervals or ±10%percentages) changed to a different value. Some examples can use Table1, or Table 1 with numeric adjustment, for GBR traffic other than QCI1.

FIG. 9 is a dataflow diagram illustrating an example process 900 forreceiving data, and related data items. Process 900 can be performed,e.g., by a control unit of a terminal (e.g., terminal 102 or 202). Insome examples, the control device includes one or more processors (e.g.,processor 214) configured to perform operations described below, e.g.,in response to computer program instructions of the detection module222. In some examples, the terminal can include a network interface 218configured to communicate wirelessly with one or more entry nodes 108,112 or other server(s) 204 of the network 100, 206. For clarity, inFIGS. 9 and 10 , control flow is shown using solid lines and dataflow isshown using dashed lines.

At 902, the control unit can receive, via a wireless communicationsinterface such as network interface 218, a unique identifier 904. Forexample, the control unit can receive a cell-radio network temporaryidentifier (C-RNTI) or other identifier used to scramble or otherwisemark data specific to the control unit or terminal 102, 202 operated bythe control unit. Other example identifiers can include a TC-RNTI(temporary C-RNTI), CS-RNTI (configured scheduling RNTI), SI-RNTI(system information RNTI), RA-RNTI (random-access RNTI), or P-RNTI(paging RNTI) (see, e.g., 3GPP 38.214). Operation 902 can be performedbefore, concurrently with, or after operation 906. As used herein, theterm “unique identifier” and similar terms encompass both truly uniqueidentifiers (e.g., Ethernet MAC addresses that are unique byconstruction, or Version 1 UUIDs) and identifiers with a negligibleprobability of collision (non-uniqueness) (e.g., SHA256 hashes of datauniquely identifying an object, or Version 4 UUIDs).

At 906, the control unit can receive, via the wireless communicationsinterface, a subframe allocation 908 (which can represent subframeallocation 316, 422, or 818). The subframe allocation 908 can indicate aMultimedia Broadcast Multicast Service (MBMS) Single Frequency Network(MBSFN) subframe 910 (e.g., at least one of the hatched subframes 304 ofsubframe allocation 316, FIG. 3 ) of a radio frame (e.g., frame 302,FIG. 3 ). MBSFN subframe 910 can represent first subframe 410, asubframe in first subset 514 of subframes, or a subframe of subframes618,

At 912, the control unit can receive, via the wireless communicationsinterface during the MBSFN subframe 910, encoded control information914. For example, the control unit can receive transmissions on aphysical downlink control channel (PDCCH) in, e.g., at least one of thefirst two OFDM symbols of the MBSFN subframe 910. Encoded controlinformation 914 can represent data transmitted at operations 318, 424,or 820, e.g., downlink data 320, 426, or 822, or control informationassociated with either of those.

In some examples, the control unit can further determine the encodedcontrol information 914 based at least in part on the unique identifier904. For example, the control unit can perform a blind search for theencoded control information 914, and locate the encoded controlinformation 914 based on successful verification of a CRC scrambled withthe unique identifier 904. In other examples, at operation 912, thecontrol unit can store received PDCCH data for later search.

Because a subframe can include data intended for more than one terminal102, control information 914, e.g., Downlink Control Information (DCI),in a subframe (e.g., in the subframe's PDCCH) can be marked in partusing unique identifiers 904 for those terminals 102 to distinguishbetween control information 914 intended for different terminals 102. Insome examples, the unique identifiers 904 can be scrambled in thecontrol information 914 with a cyclic redundancy check (CRC) or otherchecksum, or those CRCs or checksums can be scrambled with the uniqueidentifiers 904, such that individual terminals 102 can only descramblethe portion of the control information 914 marked with their uniqueidentifier 904.

In some examples, a terminal's unique identifier 904 can be a C-RNTIthat is assigned to the terminal 102 by an entry node 108 when theterminal 102 initially connects to that entry node 108. As such, controlinformation 914 within subframes transmitted by an entry node 108 can bemarked with C-RNTIs to identify control information 914 forcorresponding terminals 102. A particular terminal 102 can accordinglyuse control information 914 that is marked with its C-RNTI to locate andinterpret resource blocks in the PDSCH that contain data for thatparticular terminal 102.

When a terminal 102 receives a new subframe from an entry node 108, itmay not know whether that particular subframe contains any data for theterminal 102. Accordingly, the terminal 102 can perform a blind searchof the PDCCH on the physical layer to determine if it contains anycontrol information 914 marked with the terminal's identifier, such asthe terminal's C-RNTI, as described above. If it does, the terminal 102can use the control information 914 marked with the terminal'sidentifier to locate and/or decode control information 914 or otherdownlink data (e.g., in the PDSCH) that is intended for that terminal102.

As discussed above, downlink data for a particular terminal 102 can beencoded differently depending on the transmission mode selected for theradio frame 302 or subframe 304 by the entry node 108 for that terminal102. Each of the multiple transmission modes can correspond to adifferent DCI format that can be used to encode the control information914 (e.g., in the PDCCH). For example, 3GPP's DCI format 2 can beassociated with TM4, while 3GPP's DCI format 2C can be associated withTM9. Because the control information 914 for a particular terminal 102can be encoded using different DCI formats depending on whichtransmission mode the entry node 108 is actually using for the terminal102 in the current radio frame 302 or subframe 304, during a blindsearch of the PDCCH the terminal 102 may only be able to identifywhether a subframe contains control information 914 marked with theterminal's identifier if the terminal 102 uses the correct DCI format tointerpret the control information 914. This permits each terminal 102 toidentify its own encoded control information 914.

At 916, the control unit can determine a downlink transmission mode(DTM) 918 based at least in part on the encoded control information 914and the unique identifier. In some examples, the encoded controlinformation 914 comprises a DCI record listing the DTM 918 (e.g.,encoded as an ASN.1 ENUMERATED or other type). Additionally oralternatively, the DCI record can include a format indicator, or (asdiscussed above) be of a specific format, that is uniquely associatedwith a particular DTM. In this way, the presence of the DCI record ofthat format indicates the DTM 918. In some examples, the DTM 918 is TM9.DTM 918 can represent a DTM 308 or other element of set 312 of DTMs;second DTM 418; predetermined DTM 518, 608; or a DTM 812 or otherelement of set 814 of DTMs.

In some examples, the control unit can determine the DTM 918 furtherbased at least in part on the unique identifier 904. For example, thecontrol unit can verify a CRC of a DCI record listing or associated withthe DTM 918 using the unique identifier 904.

In some examples, the control unit can determine other networkparameters, e.g., by decoding upper-layer messages carried in theencoded control information 914. For example, based on received encodedcontrol information 914 at the PHY layer, the control unit can decodeMAC, RLC, PDCP, and RRC layers (in that order) to extract anRRCConnectionReconfiguration message. The RRCConnectionReconfigurationmessage can indicate, e.g., the rate 528, 612, or 708 ofreference-signal transmission, or other parameters of the network.

At 920, the control unit can receive data 922 using the DTM during theMBSFN subframe 910. This can permit multiplexing transmission modeswithin a single radio frame, which is not possible in some priorschemes. Data 922 can represent DL data 320, 426, or 822, or controlinformation associated therewith, as discussed above.

In some examples, the control unit can receive the data 922 furtherbased at least in part on the unique identifier 904. For example, thecontrol unit can descramble PDSCH data 922 using the unique identifier904, or verify a checksum of the data 922 using the unique identifier904.

In some examples, the unique identifier 904 is an input to exactly oneof operations 912, 916, and 920 (shown as “at least one of”). In otherexamples, the unique identifier 904 is an input to more than one of(e.g., all of) operations 912, 916, and 920.

FIG. 10 is a dataflow diagram illustrating an example process 1000 forreceiving data, and related data items. Process 1000 can be performed,e.g., by a control unit of a terminal (e.g., terminal 102 or 202), e.g.,in response to computer program instructions of the detection module222. In some examples, operation 906 is followed by operation 1004. Insome examples, operation 912 is followed by operation 1016.

In some examples of process 1000, the subframe allocation 908 furtherindicates anon-MBSFN subframe 1002 of the radio frame (e.g., radio frame302). The non-MBSFN subframe 1002 can be a different subframe from theMBSFN subframe 910. Non-MBSFN subframe 1002 can represent first subframe410, a subframe in first subset 514 of subframes, or a subframe ofsubframes 618,

At 1004, the control unit can receive, via the wireless communicationsinterface during the non-MBSFN subframe, second encoded controlinformation 1006 (e.g., PDCCH values). Examples are discussed herein,e.g., with reference to operation 912. The control unit can determinethe second encoded control information 1006 further based at least inpart on the unique identifier 904, although this is not required in allexamples. Second encoded control information 1006 can represent datatransmitted at operations 318, 424, or 820, e.g., downlink data 320,426, or 822, or control information associated with either of those.

At 1008, the control unit can determine a second DTM 1010 based at leastin part on the second encoded control information. Examples arediscussed herein, e.g., with reference to operation 916. In someexamples, the second DTM 1010 is different from the DTM 918. The controlunit can determine the second DTM 1010 further based at least in part onthe unique identifier 904, although this is not required in allexamples. Second DTM 1010 can represent a DTM 308 or other element ofset 312 of DTMs; second DTM 418; predetermined DTM 518, 608; or a DTM812 or other element of set 814 of DTMs.

At 1012, the control unit can receive second data 1014 using the secondDTM 1010 during the non-MBSFN subframe 1002. Examples are discussedherein, e.g., with reference to operation 920. The control unit canreceive or determine the second data 1014 further based at least in parton the unique identifier 904, although this is not required in allexamples. Second data 1014 can represent DL data 320, 426, or 822, orcontrol information associated therewith, as discussed above.

At 1016, in some examples, the control unit can determine, based atleast in part on the encoded control information 914 (and, in someexamples, on the unique identifier 904), a rate 1018 of transmission ofreference signals. For example, the rate 1018 can be carried in anRRCConnectionReconfiguration or other message at a layer higher than thePHY, or in a PHY-specific message. In some examples, the rate 1018 canbe represented as a span of time (e.g., expressed in terms of OFDMsymbols) between reference-signal transmissions. In some examples, therate can be represented as one or more resource-element locations inwhich reference signals are transmitted. The determined rate canrepresent rate 528, 612, or 708.

At 1020, the control unit can receive the reference signals based atleast in part on the rate 1018. For example, the control unit canextract resource-element locations from the rate 1018, or determineresource-element locations based on time-span or -offset parametersindicated in the rate 1018. The control unit can then receive data ofthose resource elements and treat the received data as data of areference signal.

Various examples of process 1000 permit using two transmission modesduring a frame. For example, a terminal 102 may have a traffic mix andradio environment that is able to take advantage of both TM4 and TM9.Process 1000 can permit doing so. Additionally or alternatively, DTM 918can be an LTE DTM and second DTM 1010 can be an NR DTM (or,equivalently, an NR downlink transmission scheme, 3GPP 38.214), or viceversa. Process 1000 can permit a dual-connectivity terminal 102 tocommunicate effectively via overlaid LTE and NR, or other combinationsof access networks.

Example Clauses

Various examples include one or more of, including any combination ofany number of, the following example features. Throughout these clauses,parenthetical remarks are for example and explanation, and are notlimiting.

A: A network base station, comprising: a communications interfaceconfigured to communicate wirelessly with one or more terminals of thenetwork; and a control unit connected with the communications interfaceand configured to perform operations comprising: selecting, for each ofthe one or more terminals, a respective downlink transmission mode (DTM)based at least in part on respective channel condition information(CCI), wherein the respective DTMs are selected from a predetermined setof DTMs; determining a subframe allocation based at least in part on theselected DTMs, wherein the subframe allocation indicates exactly one DTMof the predetermined set of DTMs for each of a plurality of subframes ofa radio frame; and transmitting downlink data to at least one of the oneor more terminals using the communications interface based at least inpart on the subframe allocation.

B: The network base station according to paragraph A, the operationsfurther comprising: receiving, using the communications interface, therespective channel condition information for at least one of the one ormore terminals.

C: The network base station according to paragraph A or B, wherein: thepredetermined set of DTMs consists of Third-Generation PartnershipProject Transmission Mode Four and Third-Generation Partnership ProjectTransmission Mode Nine; the subframe allocation indicates a first subsetof the plurality of subframes and a second, disjoint subset of theplurality of subframes; the subframe allocation assigns the subframes ofthe first subset as Multimedia Broadcast Multicast Service (MBMS) SingleFrequency Network (MBSFN) subframes associated with Transmission ModeNine; and the subframe allocation assigns the subframes of the secondsubset as non-MBSFN subframes associated with Transmission Mode Four.

D: The network base station according to any of paragraphs A-C, theoperations further comprising: transmitting a terminal-specificreference signal to a first terminal of the one or more terminals usingthe communications interface based at least in part on the subframeallocation; subsequently, receiving second CCI associated with theterminal-specific reference signal; and selecting a second DTM for thefirst terminal based at least in part on the second CCI.

E: The network base station according to paragraph D, the operationsfurther comprising: determining a second subframe allocation based atleast in part on the second DTM; and transmitting second downlink datato the first terminal using the communications interface based at leastin part on the second subframe allocation.

F: The network base station according to paragraph D or E, wherein: thefirst subframe allocation assigns a first subframe of the plurality ofsubframes as an MBSFN subframe associated with Third-GenerationPartnership Project Transmission Mode Nine; and the operations comprise:transmitting the terminal-specific reference signal during the firstsubframe; and determining the second subframe allocation assigning thefirst subframe as a non-MBSFN subframe associated with Third-GenerationPartnership Project Transmission Mode Four.

G: The network base station according to any of paragraphs A-F, whereinthe network base station is associated with a first access network of afirst type, the operations further comprising: receiving, from a secondbase station associated with a second access network of a second,different type, second-network load information of the second accessnetwork; determining the subframe allocation based at least in part onthe second-network load information, wherein the subframe allocationindicates, for each subframe of the plurality of subframes, whether thatsubframe is associated with the first access network or the secondaccess network; and transmitting at least a portion of the subframeallocation to the second base station.

H: The network base station according to paragraph G, the operationsfurther comprising, before receiving the second-network loadinformation, sending a request for the second-network load informationto the second base station.

I: The network base station according to any of paragraphs A-H, wherein:the network base station further comprises a full-dimensionmultiple-input multiple-output (FD-MIMO) antenna array connected withthe communications interface; and the operations comprise transmittingat least some of the downlink data to a first terminal of the one ormore terminals in a formed beam using the FD-MIMO antenna array.

J: The network base station according to any of paragraphs A-I, wherein:the subframe allocation indicates a first subset of the plurality ofsubframes and a second, disjoint subset of the plurality of subframes;the first subset is associated with a predetermined DTM of thepredetermined set of DTMs; and the operations further comprise:determining a first proportion of traffic being carried by the networkbase station that is first traffic, wherein the first traffic: isguaranteed bit-rate (GBR) traffic; and is associated with thepredetermined downlink transmission mode (DTM); determining, based atleast in part on the first proportion, a first rate of transmission ofreference signals associated with the predetermined DTM; andtransmitting the reference signals associated with the predetermined DTMsubstantially at the first rate and during one or more subframes of thefirst subset.

K: A method comprising, by a network base station in a wireless network:determining a first proportion of traffic being carried by the networkbase station that is first traffic, wherein the first traffic: isguaranteed bit-rate (GBR) traffic; and is associated with terminalscommunicating with the network base station using a predetermineddownlink transmission mode (DTM); determining, based at least in part onthe first proportion, a first rate of transmission of reference signalsassociated with the predetermined DTM; and transmitting the referencesignals associated with the predetermined DTM substantially at the firstrate and during one or more subframes associated with the predeterminedDTM.

L: The method according to paragraph K, further comprising, by thenetwork base station, after determining the first rate: determining asecond proportion of traffic being carried by the network base stationthat is first traffic; determining, based at least in part on the secondproportion, a second rate of transmission of reference signalsassociated with the predetermined DTM; and transmitting the referencesignals associated with the predetermined DTM substantially at thesecond rate and during the one or more subframes associated with thepredetermined DTM; wherein: the first proportion is higher than thesecond proportion; and the first rate is higher than the second rate.

M: The method according to paragraph K or L, wherein: the predeterminedDTM is Third-Generation Partnership Project Transmission Mode Nine; andthe reference signals associated with the predetermined DTM areChannel-State Information-Reference Signal (CSI-RS) signals.

N: The method according to any of paragraphs K-M, further comprising, bythe network base station: determining a subframe allocation based oninformation of a plurality of terminals attached to the network basestation, wherein: the subframe allocation indicates, for each of aplurality of subframes of a radio frame, exactly one DTM of apredetermined set of DTMs; the predetermined set of DTMs comprises thepredetermined DTM; and the subframe allocation indicates the one or moresubframes associated with the predetermined DTM; and transmittingdownlink data to at least a first terminal of the plurality of terminalsduring a first subframe of the one or more subframes associated with thepredetermined DTM based at least in part on the subframe allocation.

O: The method according to paragraph N, further comprising, by thenetwork base station: selecting, for each of the plurality of terminalsattached to the network base station, a respective DTM based at least inpart on respective channel condition information (CCI), wherein therespective DTMs are selected from the predetermined set of DTMs.

P: The method according to paragraph O, wherein: the method furthercomprises, by the network base station: transmitting a firstterminal-specific reference signal of the reference signals to the firstterminal in one of the one or more subframes associated with thepredetermined DTM; and receiving first CCI from the first terminal; andthe first CCI is associated with the first terminal-specific referencesignal.

Q: The method according to any of paragraphs N-P, wherein: the subframeallocation indicates a first subset of the plurality of subframes and asecond, disjoint subset of the plurality of subframes; the first subsetcomprises the one or more subframes associated with the predeterminedDTM; the predetermined DTM is Third-Generation Partnership ProjectTransmission Mode Nine; the subframe allocation assigns the subframes ofthe first subset as Multimedia Broadcast Multicast Service (MBMS) SingleFrequency Network (MBSFN) subframes associated with Transmission ModeNine; and the subframe allocation assigns the subframes of the secondsubset as non-MBSFN subframes.

R: One or more computer-readable media comprising instructions that,when executed by at least one processor, cause the at least oneprocessor to perform operations comprising: receiving, via a wirelesscommunications interface, a unique identifier; receiving, via thewireless communications interface, a subframe allocation indicating aMultimedia Broadcast Multicast Service (MBMS) Single Frequency Network(MBSFN) subframe of a radio frame; receiving, via the wirelesscommunications interface during the MBSFN subframe, encoded controlinformation; determining a downlink transmission mode (DTM) based atleast in part on the encoded control information; and receiving datausing the DTM during the MBSFN subframe, wherein the operations furthercomprise at least one of: determining the encoded control informationfurther based at least in part on the unique identifier; determining theDTM further based at least in part on the unique identifier; orreceiving the data further based at least in part on the uniqueidentifier.

S: The one or more computer-readable media according to paragraph R,wherein: the subframe allocation further indicates a non-MBSFN subframeof the radio frame, the non-MBSFN subframe different from the MBSFNsubframe; and the operations further comprise: receiving, via thewireless communications interface during the non-MBSFN subframe, secondencoded control information; determining a second DTM based at least inpart on the second encoded control information, the second DTM differentfrom the DTM; and receiving second data using the second DTM during thenon-MBSFN subframe.

T: The one or more computer-readable media according to paragraph R orS, wherein: the encoded control information comprises a Downlink ControlInformation (DCI) record; and the DTM is Third-Generation PartnershipProject Transmission Mode Nine.

U: The one or more computer-readable media according to any of claimsR-T, the operations further comprising: determining, based at least inpart on the encoded control information, a rate of transmission ofreference signals; and receiving the reference signals based at least inpart on the rate.

V: A computer-readable medium, e.g., a computer storage medium, havingthereon computer-executable instructions, the computer-executableinstructions upon execution configuring a computer to perform operationsas any of paragraphs A-J, K-Q, or R-U recites.

W: A device comprising: a processor; and a computer-readable medium,e.g., a computer storage medium, having thereon computer-executableinstructions, the computer-executable instructions upon execution by theprocessor configuring the device to perform operations as any ofparagraphs A-J, K-Q, or R-U recites.

X: A system comprising: means for processing; and means for storinghaving thereon computer-executable instructions, the computer-executableinstructions including means to configure the system to carry out amethod as any of paragraphs A-J, K-Q, or R-U recites.

AB: A network terminal configured to perform operations as any ofparagraphs R-U recites.

AC: A network control device configured to perform operations as any ofparagraphs A-J or K-Q recites.

CONCLUSION

Various aspects described above permit load-balancing radio resourcesbetween transmission modes, access networks, or both. Various aspectspermit adjusting reference-signal transmission rates depending on thetype of traffic, to provide increased reliability of GBR traffic andincreased capacity of non-GBR traffic. As discussed above, technicaleffects of various examples can include controlling bandwidth usage,reducing network load, and increasing network reliability.

Example components FIGS. 1 and 2 , example data exchanges and processblocks in FIGS. 3-10 , and other methods, processes, or operationsdescribed above can be embodied in, and fully automated via, hardware,firmware, or software code modules embodied in or executed by one ormore computers, processors, or other control units. As used herein, theterm “module” is intended to represent example divisions of thedescribed operations for purposes of discussion, and is not intended torepresent any type of requirement or required method, manner ororganization. Therefore, while various “modules” are discussed herein,their functionality and/or similar functionality can be arrangeddifferently (e.g., combined into a smaller number of modules, brokeninto a larger number of modules, etc.). In some instances, thefunctionality and/or modules discussed herein may be implemented as partof a computer operating system (OS). In other instances, thefunctionality and/or modules may be implemented as part of a devicedriver, firmware, application, or other software subsystem. Softwareimplementing the techniques described above can be distributed onvarious types of computer-readable media, not limited to the forms ofmemory that are specifically described.

Example computer-implemented operations described herein canadditionally or alternatively be embodied in specialized computerhardware, e.g., FPGAs. For example, various aspects herein may take theform of an entirely hardware aspect, an entirely software aspect(including firmware, resident software, micro-code, etc.), or an aspectcombining software and hardware aspects. These aspects can all generallybe referred to herein as a “service,” “circuit,” “circuitry,” “module,”or “system.”

Many variations and modifications can be made to the above-describedexamples, the elements of which are to be understood as being amongother acceptable examples. All such modifications and variations areintended to be included herein within the scope of this disclosure andprotected by the claims. For example, structures or operations describedwith respect to a single server or device can be performed by each ofmultiple devices, independently or in a coordinated manner, except asexpressly set forth herein. Similarly, although some features andexamples herein have been described in language specific to structuralfeatures and/or methodological steps, it is to be understood that theappended claims are not necessarily limited to the specific features orsteps described herein. Rather, the specific features and steps aredisclosed as preferred forms of implementing the claimed invention. Forexample, network 206, processors 214 and 230, and other structures orsystems described herein for which multiple types of implementingdevices or structures are listed can include any of the listed types,and/or multiples and/or combinations thereof.

Some operations of example processes or devices herein are illustratedin individual blocks and logical flows thereof, and are summarized withreference to those blocks. The order in which the operations aredescribed is not intended to be construed as a limitation unlessotherwise indicated. Any number of the described operations can beexecuted, or data transmissions performed, in any order, combined in anyorder, subdivided into multiple sub-operations, or executed in parallelto implement the described processes. For example, in alternativeimplementations included within the scope of the examples describedherein, elements or functions can be deleted, or executed out of orderfrom that shown or discussed, including substantially synchronously orin reverse order.

Moreover, this disclosure is inclusive of combinations of the aspectsdescribed herein. References to “a particular aspect” (or “embodiment”or “version”) and the like refer to features that are present in atleast one aspect of the invention. Separate references to “an aspect”(or “embodiment”) or “particular aspects” or the like do not necessarilyrefer to the same aspect or aspects; however, such aspects are notmutually exclusive, unless so indicated or as are readily apparent toone of skill in the art. The use of singular or plural in referring to“method” or “methods” and the like is not limiting.

The word “or” and the phrase “and/or” are used herein in an inclusivesense unless specifically stated otherwise. Accordingly, conjunctivelanguage such as, but not limited to, at least one of the phrases “X, Y,or Z,” “at least X, Y, or Z,” “at least one of X, Y or Z,” “one or moreof X, Y, or Z,” and/or any of those phrases with “and/or” substitutedfor “or,” unless specifically stated otherwise, is to be understood assignifying that an item, term, etc., can be either X, or Y, or Z, or acombination of any elements thereof (e.g., a combination of XY, XZ, YZ,and/or XYZ). Any use herein of phrases such as “X, or Y, or both” or “X,or Y, or combinations thereof” is for clarity of explanation and doesnot imply that language such as “X or Y” excludes the possibility ofboth X and Y, unless such exclusion is expressly stated.

As used herein, language such as “one or more Xs” shall be consideredsynonymous with “at least one X” unless otherwise expressly specified.Any recitation of “one or more Xs” signifies that the described steps,operations, structures, or other features may, e.g., include, or beperformed with respect to, exactly one X, or a plurality of Xs, invarious examples, and that the described subject matter operatesregardless of the number of Xs present, as long as that number isgreater than or equal to one.

Conditional language such as, among others, “can,” “could,” “might” or“may,” unless specifically stated otherwise, are understood within thecontext to present that certain examples include, while other examplesdo not include, certain features, elements and/or steps. Thus, suchconditional language is not generally intended to imply that certainfeatures, elements and/or steps are in any way required for one or moreexamples or that one or more examples necessarily include logic fordeciding, with or without user input or prompting, whether certainfeatures, elements and/or steps are included or are to be performed inany particular example.

In the claims, any reference to a group of items provided by a precedingclaim clause is a reference to at least some of the items in the groupof items, unless specifically stated otherwise. This document expresslyenvisions alternatives with respect to each and every one of thefollowing claims individually, in any of which claims any such referencerefers to each and every one of the items in the corresponding group ofitems. Furthermore, in the claims, unless otherwise explicitlyspecified, an operation described as being “based on” a recited item canbe performed based on only that item, or based at least in part on thatitem. This document expressly envisions alternatives with respect toeach and every one of the following claims individually, in any of whichclaims any “based on” language refers to the recited item(s), and noother(s). Additionally, in any claim using the “comprising” transitionalphrase, a recitation of a specific number of components (e.g., “two Xs”)is not limited to embodiments including exactly that number of thosecomponents, unless expressly specified (e.g., “exactly two Xs”).However, such a claim does describe both embodiments that includeexactly the specified number of those components and embodiments thatinclude at least the specified number of those components.

What is claimed is:
 1. A method, comprising: transmitting, by a firstterminal in a wireless network and to a network base station, firstchannel condition information (CCI) utilized by the network base stationto select a first downlink transmission mode (DTM) that is differentfrom a second DTM used for a second terminal, the second DTM beingselected by the network base station based at least in part on secondCCI associated with the second terminal; and receiving, by the firstterminal using the first DTM, first data and a first channel selectioninformation reference signal (CSI-RS), based at least in part on thefirst DTM for the first terminal and the second DTM for the secondterminal being assigned by a subframe allocation determined by thenetwork base station, the first CSI-RS being received at a first CSI-RStransmission rate determined by the network base station based at leastin part on a first proportion of traffic, the first CSI-RS transmissionrate being different from a second CSI-RS transmission rate associatedwith a second CSI-RS received by the second terminal and from thenetwork base station, the second CSI-RS transmission rate beingdetermined by the network base station based at least in part on asecond proportion of traffic.
 2. The method of claim 1, furthercomprising: determining to interpret the first data in a radio frameusing the first DTM, based at least in part on a message received fromthe network base station.
 3. The method of claim 1, further comprising:receiving, from a control unit of the network base station, a radioresource control (RRC) reconfiguration message; determining to utilize athird DTM to interpret second data in a radio frame at a physical layer,based at least in part on the RRC reconfiguration message.
 4. The methodof claim 1, further comprising: receiving, from the network basestation, a control message indicating that the first DTM is selected forthe first data.
 5. The method of claim 1, further comprising: receiving,in a subset of subframes indicated in the subframe allocation, the firstCSI-RS at the first CSI-RS transmission rate.
 6. The method of claim 1,further comprising: receiving, in a subset of subframes determined bythe network base station based at least in part on the first CCI, thefirst CSI-RS.
 7. The method of claim 1, further comprising: receiving,from the network base station, the first CSI-RS in a first subset ofmultimedia broadcast multicast service (MBMS) single frequency network(MBSFN) subframes, the first subset of MBSFN subframes and a secondsubset of non-MBSFN subframes being assigned in the subframe allocation,the first subset of MBSFN subframes being assigned for the first CSI-RSbased at least in part on the first CCI, the second subset of non-MBSFNsubframes being assigned for the second CSI-RS transmitted to the secondterminal based at least in part on the second CCI.
 8. The method ofclaim 1, wherein the first CSI-RS is transmitted in a first subframeindicated in the subframe allocation determined by the network basestation, and wherein the second CSI-RS is transmitted in a secondsubframe indicated in the subframe allocation.
 9. The method of claim 1,wherein the first proportion of traffic includes a first proportion of afirst number of attached terminals, a first number of subframes beingused per unit time, or a first number of bits being communicated perunit time, and wherein the second proportion of traffic includes asecond proportion of a second number of attached terminals, a secondnumber of subframes being used per unit time, or a second number of bitsbeing communicated per unit time.
 10. A system, comprising: at least oneprocessor; and memory storing instructions that, when executed by the atleast one processor, cause the at least one processor to performoperations comprising: transmitting, by a first terminal in a wirelessnetwork and to a network base station, first channel conditioninformation (CCI) utilized by the network base station to select a firstdownlink transmission mode (DTM) that is different from a second DTMselected for a second terminal; and receiving, by the first terminalusing the first DTM and from the network base station, first data and afirst channel selection information reference signal (CSI-RS), based atleast in part on the first DTM for the first terminal being assigned bya subframe allocation determined by the network base station, the firstCSI-RS being received at a first CSI-RS transmission rate determined bythe network base station based at least in part on a first proportion oftraffic, the first CSI-RS transmission rate being different from asecond CSI-RS transmission rate associated with a second CSI-RS receivedby the second terminal and from the network base station, the secondCSI-RS transmission rate being determined by the network base stationbased at least in part on a second proportion of traffic.
 11. The systemof claim 10, the instructions further causing the at least one processorto perform operations comprising: determining to interpret the firstdata in a radio frame using the first DTM, based at least in part on amessage received from the network base station.
 12. The system of claim10, the instructions further causing the at least one processor toperform operations comprising: receiving, from a control unit of thenetwork base station, a radio resource control (RRC) reconfigurationmessage; determining to utilize a third DTM to interpret second data ina radio frame at a physical layer, based at least in part on the RRCreconfiguration message.
 13. The system of claim 10, the instructionsfurther causing the at least one processor to perform operationscomprising: receiving, from the network base station, a control messageindicating that the first DTM is selected for the first data.
 14. Thesystem of claim 10, the instructions further causing the at least oneprocessor to perform operations comprising: receiving, in a subset ofsubframes indicated in the subframe allocation, the first CSI-RS at thefirst CSI-RS transmission rate.
 15. The system of claim 10, theinstructions further causing the at least one processor to performoperations comprising: receiving, from the network base station, thefirst CSI-RS in a first subset of multimedia broadcast multicast service(MBMS) single frequency network (MBSFN) subframes assigned by thenetwork base station based at least in part on the first CCI, the firstDTM being a 3GPP transmission mode nine.
 16. The system of claim 10,wherein the first DTM is a 3GPP transmission mode nine, and the secondDTM is a 3GPP transmission mode four.
 17. The system of claim 10,wherein a first subset of multimedia broadcast multicast service (MBMS)single frequency network (MBSFN) subframes is utilized to receive thefirst data, based at least in part on the subframe allocation assigningthe MBSFN subframes for the first DTM and non-MBSFN subframes for thesecond DTM.
 18. A server, comprising: at least one processor; and memorystoring instructions that, when executed by the at least one processor,cause the at least one processor to perform operations comprising:transmitting, by a first terminal in a wireless network and to a networkbase station, first channel condition information (CCI) utilized by thenetwork base station to select a first downlink transmission mode (DTM)that is different from a second DTM selected for a second terminal; andreceiving, by the first terminal using the first DTM, first data and afirst channel selection information reference signal (CSI-RS), based atleast in part on the first DTM for the first terminal being assigned bya subframe allocation determined by the network base station, the firstCSI-RS being received at a first CSI-RS transmission rate determined bythe network base station based at least in part on a first proportion oftraffic, the first CSI-RS transmission rate being different from asecond CSI-RS transmission rate associated with a second CSI-RS receivedby the second terminal and from the network base station, the secondCSI-RS transmission rate being determined by the network base stationbased at least in part on a second proportion of traffic.
 19. The serverof claim 18, the instructions further causing the at least one processorto perform operations comprising: determining to interpret the firstdata in a radio frame using the first DTM, based at least in part on amessage received from the network base station.
 20. The server of claim18, the instructions further causing the at least one processor toperform operations comprising: receiving, from a control unit of thenetwork base station, a radio resource control (RRC) reconfigurationmessage; and determining to utilize the first DTM to interpret the firstdata in a radio frame at a physical layer, based at least in part on theRRC reconfiguration message.